Distribution boards.
Lighting & power.
CWS manufactures custom distribution boards for commercial, industrial and infrastructure projects throughout New Zealand. Lighting, socket-outlet, equipment and building-services circuits are arranged around the project schedule, protection requirements, metering, controls and installation layout.
Distribution built around the loads.
A distribution board divides an incoming supply into the circuits serving an area, floor, tenant or group of equipment. Unlike a site main switchboard, its brief is usually driven by the outgoing circuit schedule and the way those circuits need to be protected, identified and operated.
List the actual loads and their circuit requirements rather than selecting a board only by its number of ways. Single-phase and three-phase equipment, controlled lighting, essential supplies, metering and future circuits all influence the arrangement.
For a coordinated building package, link each DB to its upstream main switchboard and use consistent board names and circuit references throughout the drawings.
| Schedule field | Why it matters to the board build |
|---|---|
| Circuit reference and destination | Connects the protective device, cable and final label to the same room, equipment item or load group. |
| Load and supply characteristics | Identifies the design load, voltage, phase requirements and any equipment-specific starting or inrush information. |
| Protection specification | Records the designer’s requirements for overcurrent and residual-current protection, including equipment compatibility. |
| Control or switching | Identifies circuits requiring contactors, timers, external commands or local switching rather than protection alone. |
| Metering or monitoring | Clarifies whether consumption is measured by board, tenancy, load group or individual circuit. |
| Spare and future circuits | Distinguishes fitted spare devices from unused positions and identifies expected future loads. |
Connected load and expected simultaneous demand are different inputs. Supply the design assumptions and phase allocation, where available, so the incomer, distribution arrangement and outgoing circuits are considered together.
Choose protection for each circuit.
Overcurrent and residual-current protection
Overcurrent protection addresses overloads and short circuits. Residual-current protection addresses current imbalance associated with leakage. An RCBO combines residual-current and overcurrent protection in one device; the required device type and characteristics still need to suit the circuit.
The electrical designer’s requirements and equipment manufacturer’s instructions should guide selection. Electronic equipment, drives and other loads can introduce considerations that are not resolved by choosing an amp rating alone. See the manufacturer’s explanation of combined RCBO protection.
Fault level at the distribution board
Identify the prospective fault current at the DB and its upstream protection. A downstream location does not establish the required fault rating by itself. Device selection and any coordinated combination need supporting information for the actual installation.
Circuit grouping and continuity of service
Consider the consequence of losing a circuit or a shared protective device. Lighting, refrigeration, communications equipment and ordinary socket outlets may have different operational priorities. Define the grouping and protection approach with the project designer.
Controlled lighting and equipment supplies
Identify which circuits require switching by a lighting controller, timer, contactor or external system. Agree control supplies, manual operation and the limits of the board manufacturer’s scope. Mechanical plant sequences belong in a defined mechanical services switchboard or controls package, rather than an unexplained note on the DB schedule.
Do not assume the neutral is lightly loaded. Non-linear single-phase loads can produce harmonic currents that accumulate in the neutral. Include the load characteristics in the design review. Schneider Electric’s guide explains the effect of harmonics on neutral loading; the project design must apply the requirements relevant to the installation.
Space for cables. Capacity for change.
Enclosure and mounting
Provide the proposed location, mounting constraints and available dimensions. A board in an electrical cupboard, an industrial workspace and an exposed service area may need different enclosure arrangements. Cable entry, door opening and the required access should be checked with the installation layout.
Cable and device space
Allow for incoming cable terminations, outgoing cables, neutral and earth connections, control wiring and identification. The number of circuits alone does not determine the physical space needed, particularly where devices have different widths or additional controls are included.
Schneider Prisma G and P
CWS has accredited builder capability across both systems. Platform selection follows the required configuration and project specification; it is not a reason to apply the same board arrangement to every installation. Explore Schneider Prisma assemblies.
Metering with a defined purpose
State whether metering is for facility monitoring, energy management, tenant allocation or another purpose. Agree the measurement points, communications and required accuracy. A monitoring meter is not automatically a complete or approved billing arrangement.
Identification that remains useful
Use board names and circuit descriptions that match the drawings and the installed equipment. Agree circuit schedules and engraved labels as part of the documentation, including how fitted spares and unused positions are identified.
Future capacity
List likely future circuit types and loads, not only a percentage of spare ways. Spare physical positions do not by themselves provide extra supply capacity, suitable cable access or room for every future protective device.
Keep the circuit records aligned.
Before manufacture, agree the circuit arrangement, device schedule, mounting and cable-entry details. Record changes to the circuit list so the finished board is not built from an obsolete revision.
The completed assembly is checked and tested within the agreed factory scope. Installation work, final circuit connections and the testing required on site remain distinct responsibilities. Confirm those boundaries in the quotation and handover plan.
- Identify the source of supply and the board’s circuit references.
- Match the fitted devices and labels to the approved schedule.
- Record the declared assembly ratings and agreed factory checks.
- Provide the drawings and circuit information required for installation.
- Allocate responsibility for final circuit records after site changes.
Distribution boards within a larger project
The Southern Charity Hospital package included CWS-manufactured distribution boards alongside the main switchboard. A common equipment and documentation approach helps coordinate the separate boards without treating their functions as identical.
What to send for a quotation
Include the board schedule, single-line diagram, supply and fault-level information, protection requirements, enclosure or mounting details, cable-entry direction, metering requirements and delivery programme.
For several DBs, identify each board separately, even where the layouts are similar. Circuit counts, supplies and metering boundaries should remain traceable to each assembly.
Right-sized for the circuits, not just the cupboard.
Start with the circuit schedule you have. We can identify what is still needed before the arrangement and quotation are finalised.
Can you manufacture several matching boards for one building?
Yes. Provide the schedule for each board and identify the common equipment, labelling and documentation requirements. Each assembly still needs the correct circuit arrangement and ratings for its own supply and loads.
Can an existing enclosure be reused?
That requires an assessment of its condition, dimensions, existing arrangement and the proposed work. Reuse is not assumed to be suitable simply because the new devices fit. Send photographs, records and the proposed circuit changes for review.
Are spare ways the same as spare electrical capacity?
No. Spare ways describe physical positions. Additional load also depends on the supply, assembly rating, protective devices and wiring. State the likely future loads so both space and electrical capacity can be considered.
Put the requirements
in the brief.
Identify the standard, part and edition, current ratings, fault conditions, environment and verification records required for your project.
Understand the distinction between cited standards and subsequently published editions.
Prepare a switchboard specificationUse the enquiry checklist to prepare a comparable quotation.
Send the circuits.
We’ll shape the board.
Include the circuit schedule, incoming supply, enclosure location and any space or access constraints.
Printable quote checklist (PDF)Email your checklist, drawings and schedules to estimating@clivewilson.co.nz. Leave unknown items blank.
Request a distribution board quoteOr call +64 3 214 4264